1. Field of the Invention
This invention generally relates to computer-operated air brake control systems for railroad cars.
2. Background of the Prior Art
Electronically controlled air brake systems for multi-unit trains are generally known in the prior art. For example, U.S. Pat. No. 3,380,399 discloses a remote control and supervision system for a railroad train which employs solid state logic circuits in the brake system of a master locomotive for controlling the brake system of a slave locomotive via a radio link. A master locomotive transmits radio commands to a slave locomotive every thirty seconds in the form of a computer word comprising address, information, and check bits defining a comprehensive recapitulation of all controls. The master locomotive receives a word message in return from the slave, which relays the braking conditions present at the slave.
Another example of an electronically operated locomotive brake control system is disclosed in U.S. Pat. No. 3,560,055. Here, a manually operable brake valve on a lead locomotive effects control of an electropneumatic brake valve on a slave locomotive via radio commands. Similarly, U.S. Pat. No. 3,374,035 discloses a brake control system in which control of a multi-unit brake line is sectionalized by a main locomotive which controls the brake system of a helper locomotive by way of radio signals. Still other electronically controlled air brake systems are disclosed in U.S. Pat. Nos. 3,539,226, 3,583,771, 3,588,186, 3,799,623, 4,013,323, and 4,056,286.
Such prior art electronic air brake control systems have many advantages over older air brake controls which rely exclusively on pneumatic signals transmitted over the train air line to effect braking. Such electronic systems allow the train brakes to be applied much more simultaneously throughout multi-unit trains, thus facilitating emergency stops and reducing the stress on car couplings.
However, such prior art electronic systems are not without shortcomings. For example, the systems disclosed in U.S. Pat. Nos. 3,374,035, 3,380,399, 3,539,226, 3,560,055, 3,583,771 and 3,588,186 are designed to operate only between individual train units of multi-unit trains, rather than as between individual car units of a single train of cars. In such systems, there would still exist a lag time between the application of the brakes in the locomotive and the application of the brakes of the cars of the individual trains. Additionally, systems such as that disclosed in U.S. Pat. No. 3,380,399 are very complicated, which increases both the expense of manufacture as well as the chances of a malfunction.
While systems such as those disclosed in U.S. Pat. Nos. 3,799,623, 4,013,323, and 4,056,286 may be used on two or more cars in the same train unit, they too are not without shortcomings. For example, the systems disclosed in U.S. Pat. Nos. 4,013,323 and 4,056,286 are designed to be used only on the locomotive and the caboose of a train. While such a design can lower the lag time between the application of the various brakes of the train, it cannot eliminate it entirely. Finally, while the system disclosed in U.S. Pat. No. 3,799,623 could be used on each individual car of a train, the specific design of this system calls for a network of special electrical wiring extending the entire length of the train, which renders this system difficult to mix with conventional railroad cars which have no provision for such special wiring.
Clearly, the prior art has not yet developed an electronic air brake control system which is capable of effecting simultaneous braking between all the cars of a single train of cars, and which is fully compatible with railway cars having no special equipment.